Nylon polymers are desirable in many applications due to its outstanding elasticity, dye-fastness and high melting point. Nylon polymer commonly takes the form of pellets or flakes, which can be melted and shaped for use in plastic applications or extruded as fiber for use in yarn applications, such as apparel, carpet, airbags and outdoor gear.
Nylon resins are often formulated with additives which impart desired properties to the resin, or which solve shortcomings of a resin to make it suitable for other uses. Desired properties include thermal aging resistance and impact resistance. Typically polymer compositions often comprise fillers to modify the mechanical properties of a resin. However, if the fillers are present in large amounts the surface of the articles may have less than desirable quality.
The thermal stability of nylon polymers used for various purposes is a very critical characteristic. When plastic parts such as those used in automobiles and electrical or electronic equipment are exposed to high temperatures for a long period of time, their mechanical properties will decrease due to thermal degradation of the polymers. This kind of phenomena is known as heat aging. In order to prevent such a decrease of mechanical properties, various heat stabilizers are usually added to polymers to improve their heat aging properties. For instance, polyamides are usually stabilized with heat stabilizers including phenolic antioxidant, aromatic amines and copper or copper salt in combination with potassium iodide or potassium bromide.
Phenolic antioxidants or aromatic amines are used for stabilization at temperatures up to 130° C. Copper iodide in combination with potassium iodide and potassium halides are very expensive and the existence of copper is known to cause discoloration problems. However, the rapid developments of the automobile and electronic industries require better thermal stability of polymer materials. To that end, long term use temperatures for polyamide need to be elevated to 210° C. or even higher to 230° C. Therefore, there is a need for polyamide molding compositions which provide improved thermal aging stability along with durability. Furthermore there is a need for improved hydrolysis resistance in a resin with improved thermal aging stability.